1. Field of the Invention
The invention relates generally to medical devices and methods for their use. More particularly, the invention relates to systems and methods for steering catheters such as may be used to ablate tissues or to deliver materials within the body.
2. Related Art
In the medical field, catheters are used to deliver various therapies to locations within the body. For example, ablation catheters deliver therapy for the treatment of various diseases, such as skin spots, snoring, tumors, hemorrhage, arrhythmia and atherosclerosis. The catheters may employ a number of modalities to ablate tissue, including direct current (DC), radio frequency (RF), microwave, laser, ultrasound, chemical, cryogenic and rotary blade.
In a percutaneous procedure, one or more catheters are maneuvered into position within the body. In a typical cardiac ablation procedure, several catheters are advanced through the venous or arterial systems and positioned inside the heart. These are used to assess the etiology of the disease and then to treat it. The procedure may be iterative and make use of multiple sheaths and catheters in multiple steps. For example, in a conventional cardiac arrhythmia ablation procedure, catheters may first be maneuvered into various positions to denote the location and measure the timing of cardiac activation. This may be followed by the placement of an ablation catheter at a location with respect to the cardiac tissue where electrical activity is to be disrupted. The ablation catheter is used to burn or freeze the engaged tissue, altering the tissue behavior. Additional measurements may then be made to reassess the cardiac function. This process is repeated, alternating measurement and ablation, until the cardiac activation and resulting heart rhythm are modified as desired.
Multiple factors affect the success of such procedures. For example, one factor affecting the success of an ablation procedure is the reliability and stability of positioning (or repositioning) catheters. In an ablation procedure, the positioning not only affects the ability to take consistent measurements with a recording electrode, but also affects the ability to reliably ablate the intended target tissue. Mispositioning of the ablating element/electrode can result in failure to return to an ablation site to complete a lesion formation (an ablation), or can result in gaps in a line of lesions. These factors can make it difficult to apply the therapy, render the therapy ineffective, or even enhance the disease (e.g., make the cardiac tissue proarrhythmic).
It would therefore be desirable to provide systems and methods for facilitating positioning of catheters within the body which are more reliable, stable, and effective than prior systems and methods.